JP2859911B2 - Refractory having stabilized zirconia coating layer and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to refractories for kiln tools such as saggers, shelves, setters and the like.

(Conventional technology) Conventional kiln utensils such as saggers and shelves used as kiln utensils are exposed to high temperatures by placing an object to be fired on the surface thereof.
For example, a zirconia coating layer is formed on the surface of the refractory in contact with the object to be fired in order to suppress a reaction with the object to be fired during firing.

The zirconia coating layer is formed by, for example, spraying the surface of the sagger and press coating.

(Problems to be Solved by the Invention) However, in the refractory having such a conventional zirconia-based coating layer, since zirconia undergoes a phase transition at around 1000 ° C., shrinkage accompanying the phase transition occurs when heating and cooling are repeated. The expansion causes a pressure in the zirconia coat layer, which is one of the causes, and there is a problem that the zirconia coat layer is easily collapsed.

In order to suppress the collapse development accompanying this phase transition, stabilized zirconia that does not cause a phase transition by a thermal cycle,
Above all, it is conceivable to use calcia-stabilized zirconia which is relatively inexpensive.

However, even when a coat layer made of calcia-stabilized zirconia is provided on the surface of the refractory, if heating and cooling are repeatedly used, a phenomenon in which the coat layer peels off from the surface of the refractory due to a difference in thermal expansion tends to occur. There was a problem that it could not withstand cooling use sufficiently.

The problem to be solved by the present invention is to provide a refractory having a zirconia-based coating layer that can suppress peeling of the coating layer even when used repeatedly under such severe conditions of heating and cooling. .

The present inventor examined the microstructure of the conventional refractory having a coat layer composed of calcia-stabilized zirconia, and found that the cut surface of the refractory having the conventional coat layer was composed of two layers, a substrate and a surface coat layer. And found that adding calcia-stabilized zirconia as a main component and adding yttria-stabilized zirconia to the raw material component provides a three-layer structure of a base, an intermediate layer, and a surface coat layer. The invention has been completed.

(Means for Solving the Problems) A refractory having a stabilized zirconia-based coating layer according to the present invention for solving the above-mentioned problems is a refractory having a stabilized zirconia-based coating layer, comprising alumina and silica. An intermediate layer for enhancing the peel resistance of the surface coat layer is formed between the substrate and the surface coat layer.

A method for producing a refractory having a stabilized zirconia-based coating layer on the second surface according to the second aspect of the present invention uses calcia-stabilized zirconia and yttria-stabilized zirconia as raw materials, and kneaded a material containing the raw materials with alumina and silica. The method is characterized in that an intermediate layer is formed between the substrate and the surface coat layer to enhance the peel resistance of the surface coat layer between the substrate and the surface coat layer.

In the production method according to the second invention, the content of the yttria-stabilized zirconia is 1 with respect to the total amount of the calcia-stabilized zirconia and the yttria-stabilized zirconia.
It is desirable that the content be in the range of 1010 wt%. As is clear from the experimental data described later, it was found that the intermediate layer was formed only by adding a small amount of yttria-stabilized zirconia, and that the intermediate layer greatly increased the peeling resistance of the surface coat layer. Because. In addition, since yttria-stabilized zirconia is more expensive than calcia-stabilized zirconia, the content of yttria-stabilized zirconia is desirably 10 wt% or less. This is because even if the content exceeds 10% by weight, a drastic improvement in peeling resistance cannot be obtained. As a refractory as a mass-produced product, the content of yttria-stabilized zirconia is practically sufficient at 10 wt% or less.

As the substrate (refractory) on which the stabilized zirconia coat layer is formed, it is desirable to use a fixed refractory containing alumina and silica, such as mullite and cordierite.
After the substrate is coated with stabilized zirconia,
When used for kiln tools such as setters and shelves, the reaction between the stabilized zirconia-based coating layer and the object to be fired is difficult to proceed, and an intermediate layer between the substrate and the surface coating layer is formed. This is effective because the adhesion to the coat layer is strengthened, the thermal shock resistance is high, and the cost is low.

The kneaded material used as the raw material for forming the stabilized zirconia coating layer is adjusted to a state suitable for coating by adding a small amount of an organic binder and a solvent such as water in addition to calcia-stabilized zirconia and yttria-stabilized zirconia. It is desirable.

After applying this kneaded material to a substrate and drying, for example, 1400
Firing for several hours at a high temperature of ℃. The firing time or firing method can be appropriately changed depending on the composition and components of the substrate, but the present invention is not limited to these.

The present invention provides a refractory having a stabilized zirconia-based coating layer obtained by a production method, in which an intermediate layer having high peeling resistance is formed between a substrate and a surface coating layer. Even if high temperature and low temperature are repeatedly used during heating and cooling during baking, peeling and collapse of the stabilized zirconia coating layer can be suppressed, and the number of times of use can be greatly improved.

EXAMPLES Hereinafter, the contents of the present invention will be more specifically clarified by showing experimental data according to examples of the present invention.

Test Example 1 Test Example 1 is an example in which a stabilized zirconia coat layer was formed on a mullite sagger (base). The raw material of the coat layer was composed mainly of calcia-stabilized zirconia, a predetermined amount of yttria-stabilized zirconia was added, an organic binder and water were added to these raw materials, and the mixture was stirred and mixed to obtain a kneaded product. This kneaded material was applied to the surface of a 100 × 100 × 15 mm mullite sagger, dried at room temperature, and then kept at 1400 ° C. for 5 hours and fired.

The resulting sagger having a stabilized zirconia coating layer was subjected to microscopic observation of the microstructure of the cut surface and a peeling resistance test. The test conditions and test results are as shown in Table 1.

Microscope Observation Microscope observation was performed by cutting the sagger and observing the cut surface near the stabilized zirconia coat layer with a microscope. As a result, Comparative Example 1 in Table 1 had a two-layer structure of the substrate and the surface coat layer. On the other hand, in Examples 1 to 4, an intermediate layer was formed between the substrate and the surface coat layer, and the thickness of the intermediate layer was as shown in Table 1.

The crystal structures of the cut surfaces of Example 2 and Comparative Example 1 are as shown in the micrographs shown in FIG. 1 and FIG.
In Example 2 shown in FIG. 1, a film-like intermediate layer 3 is formed between the substrate 1 and the surface coat layer 2, and the intermediate layer is also formed on the porous portion, which is the upper coat layer of the intermediate layer 3. I'm stuck.
On the other hand, Comparative Example 1 is composed of the substrate 1 and the surface coat layer 2 and has no intermediate layer.

Peeling Resistance Test In the peeling resistance test, an operation of keeping the inside of a kiln at 1400 ° C. for 2 hours and then naturally cooling was repeated, and the number of times the coat layer was peeled was evaluated. The results were as shown in Table 1. It can be seen that in Examples 1 to 4 in comparison with Comparative Example 1, the number of passing kiln circuits was large and the peeling resistance was good.

Test Example 2 Test Example 2 is an example in which a stabilized zirconia coat layer was formed on a cordierite sagger (base). In this manufacturing method, the firing temperature was set to 1350 ° C., and the other conditions were the same as in Test Example 1.

With respect to the sagger having the stabilized zirconia-based coating layer, a cut surface near the cut coating layer was observed with a microscope and a peeling resistance test was performed. Table 2 shows the test conditions and test results. Here, the holding temperature in the peeling resistance test is 1300 ° C
Set to.

In Examples 5 to 8, an intermediate layer was observed between the substrate and the surface coat layer, but in Comparative Example 2, no intermediate layer was observed.
As a result of the peeling resistance test, in Examples 5 to 8, the number of passing kiln circuits leading to the peeling of the coat layer was 30 times or more as compared with Comparative Example 2,
It was found that the peel resistance was good.

(Effect of the Invention) As described above, according to the refractory having the stabilized zirconia-based coat layer of the present invention, an intermediate layer that increases the peel strength of the surface coat layer is formed between the substrate and the surface coat layer. Because of this microstructure, the intermediate layer has the effect of improving the peel resistance of the stabilized zirconia coating layer and greatly increasing the durability of the refractory.

[Brief description of the drawings]

FIG. 1 is a micrograph showing a crystal structure of a cut surface of a refractory having a stabilized zirconia coating layer according to the present invention, and FIG. 2 is a micrograph showing a crystal structure of a cut surface of a refractory according to a conventional example. 1 ... substrate, 2 ... surface coat layer, 3 ... intermediate layer.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 41/80-41/91

Claims (3)

(57) [Claims] 1. A refractory having a stabilized zirconia coating layer, wherein an intermediate layer is formed between a substrate containing alumina and silica and a surface coating layer to increase the peel resistance of the surface coating layer. A refractory having a stabilized zirconia coating layer characterized by the following. 2. A method comprising using calcia-stabilized zirconia and a predetermined amount of yttria-stabilized zirconia as raw materials, applying a kneaded product containing the raw materials to a substrate containing alumina and silica, and baking the mixture to form a mixture between the substrate and the surface coat layer. Forming a refractory having a stabilized zirconia coating layer, wherein an intermediate layer for increasing the peeling strength of the surface coating layer is formed on the surface coating layer. 3. The stabilized zirconia material according to claim 2, wherein the content of the yttria-stabilized zirconia is 1 to 10% by weight based on the total amount of the calcia-stabilized zirconia and the yttria-stabilized zirconia. A method for producing a refractory having a coat layer.